1. Field of the Invention
This invention relates to a system for protecting a submersible motor from inadvertent leakage into the motor housing of surrounding fluids, which could result in the electrical failure of the motor.
2. Description of the Prior Art
Submersible motors have long been employed in a number of industrial fields and are particularly useful when disposed at the bottom of an oil well for the purpose of driving a pump to lift the production fluid out of the well. In many environments, and particularly at the bottom of a fairly deep well, it is well known that the ambient pressure of the fluids surrounding the submersible electric motor is on the order of several thousand p.s.i. With pressures of this sort of magnitude, leakage of the well fluids into the motor chamber has been common. Such leakage can occur either through the seals surrounding the rotating power shaft, which necessarily must extend out of the motor housing, through the seals provided around the electrical conduit at the point that it enters the motor housing, or at casing joints. The efforts of the prior art have been in the direction of attempts to improve such seals, and have necessarily resulted in expensive configurations which still do not provide the desired degree of reliability under high differential pressure conditions.
A commercially available scheme has been developed to equalize the pressure between the motor housing and the surrounding well fluids by use of bellows or inter-connected auxiliary chambers.
Additionally, U.S. Pat. No. 2,002,912 to Mendenhall, et al, approached the problem by equalizing the pressure of the insulating fluid in the motor housing with that of the surrounding well fluids, but employed a complicated electrical sensing arrangement responsive to the well fluid level in a balance chamber to control the addition of insulating fluid to the motor housing.
There is, therefore, a need for an improved simplified system for protecting the interior of a submerged electric motor housing from the deleterious effects of surrounding fluids leaking into such housing through the various necessary seals provided on such housing.